Flight Details
The certificated commercial pilot and the sole passenger departed on an on-demand air taxi flight over remote terrain. The passenger was conducting moose counting research for the Alaska Department of Fish and Game. The airplane carried four hours of fuel divided between two wing-mounted fuel tanks, each equipped with an electric fuel gauge.
Engine Failure Sequence
After flying for two hours with the left fuel tank selected, the fuel in the left tank was almost exhausted, and the pilot switched to the right fuel tank. He then flew for about 1.5 hours on the right tank before the engine suddenly quit. The pilot switched back to the left tank and climbed to about 1,000 feet above the ground. After about 6 minutes on the left tank, the engine quit running again.
Emergency Landing
The pilot selected an emergency landing area on a small, frozen pond. The surface of the pond contained slushy ice and drifted snow. During the landing roll, the airplane entered deep snow and nosed over.
Passenger Observations
The passenger reported she flew in the accident airplane two days before the accident. During that flight, she noticed the right fuel gauge in the airplane was inoperative. During the accident flight, two days later, she again noticed the right fuel gauge was still inoperative.
Post-Accident Observations
Following recovery of the airplane, evidence of fuel staining was observed on the upper surface of the right wing, adjacent to the right fuel cap.